Manufacturing method of micro light emitting diode device

ABSTRACT

A method for manufacturing a micro light emitting diode device is provided. A plurality of first type epitaxial structures are formed on a first substrate and the first type epitaxial structures are separated from each other. A first connection layer and a first adhesive layer are configured between the first type epitaxial structures and the first substrate. The first connection layer is connected to the first type epitaxial structures. The first adhesive layer is located between the first connection layer and the first type epitaxial substrate. The Young&#39;s modulus of the first connection layer is larger than the Young&#39;s modulus of the first adhesive layer. The first connection layer located between any two adjacent first type epitaxial structures is removed so as to form a plurality of first connection portions separated from each other. Each of the first connection portions is connected to the corresponding first type epitaxial structure.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of and claims the prioritybenefit of U.S. application Ser. No. 15/803,864, filed on Nov. 6, 2017,now allowed, which claims the priority benefit of China applicationserial no. 201710685744.5, filed on Aug. 8, 2017. The entirety of eachof the above-mentioned patent applications is hereby incorporated byreference herein and made a part of this specification.

BACKGROUND OF THE INVENTION Field of the Invention

The invention is related to a light emitting device and a manufacturingmethod thereof, and particularly to a micro light emitting diode deviceand a manufacturing method thereof.

Description of Related Art

Existing manufacturing steps of micro light emitting diode device arecarried out as follows. First of all, a plurality of epitaxialstructures are formed on a growth substrate, and a required electrode isformed on each of the epitaxial structures. A first adhesive layer isformed on the growth substrate to cover each of the epitaxial structuresand the electrode thereof. Thereafter, the first substrate is adhered tothe first adhesive layer and the growth substrate is removed. At thispoint, relative positions of the epitaxial structures are fixed by thefirst adhesive layer. Subsequently, a second substrate is adhered to theepitaxial structures and the first adhesive layer via a second adhesivelayer. Lastly, the epitaxial structures are transferred to a circuitsubstrate.

In the process where the second substrate is adhered to the firstadhesive layer via the second adhesive layer, it is required that thesecond adhesive layer is heated and the second substrate is laminatedwith the second adhesive layer. At this point, the first adhesive layerthat is subjected to heat or force begins to flow and causes impact onthe epitaxial structures; as a result, the relative positions of theepitaxial structures are shifted. That is to say, when the epitaxialstructures are transferred to the circuit substrate, the defectsgenerated in the above-described manufacturing steps cause theelectrodes on each of the epitaxial structures unable to be preciselyaligned with the electrical point on the circuit substrate, whichaffects the manufacturing efficiency, yield of rate and reliability ofproduct.

SUMMARY OF THE INVENTION

The invention provides a micro light emitting diode device which hasgood reliability.

The invention provides a manufacturing method of a micro light emittingdiode device which is capable of improving manufacturing efficiency andyield of rate.

The manufacturing method of the micro light emitting diode device of theinvention includes the following manufacturing steps. (a) A plurality offirst type epitaxial structures are formed on a first substrate, and thefirst type epitaxial structures are separated from each other, wherein afirst connection layer and a first adhesive layer are configured betweenthe first type epitaxial structures and the first substrate. The firstconnection layer is connected to the first type epitaxial structures,and the first adhesive layer is located between the first connectionlayer and the first substrate, wherein the Young's modulus of the firstconnection layer is larger than the Young's modulus of the firstadhesive layer. (b) The first connection layer located between any twoadjacent first type epitaxial structures is removed so as to form aplurality of first connection portions separated from each other,wherein each of the first connection portions is connected to acorresponding first type epitaxial structure respectively.

In an embodiment of the invention, the manufacturing method of the microlight emitting diode device further includes (c) bonding a portion ofthe first type epitaxial structures to a target substrate electrically.

In an embodiment of the invention, the manufacturing method of the microlight emitting diode device further includes (d) forming a plurality ofsecond type epitaxial structures on a second substrate and the secondtype epitaxial structures are separated from each other, wherein asecond connection layer and a second adhesive layer are configuredbetween the second type epitaxial structures and the second substrate.The second connection layer is connected to the second type epitaxialstructures, and the second adhesive layer is located between the secondconnection layer and the second substrate, wherein the Young's modulusof the second connection layer is larger than the Young's modulus of thesecond adhesive layer; (e) removing the second connection layer locatedbetween any two adjacent second type epitaxial structures so as to forma plurality of a second connection portions separated from each other,wherein each of the second connection portions is connected to acorresponding second type epitaxial structure respectively.

In an embodiment of the invention, the manufacturing method of the microlight emitting diode device further includes (f) bonding a portion ofthe first type epitaxial structures in step (b) to the target substrateelectrically; (g) bonding a portion of the second type epitaxialstructures in step (e) to the target substrate electrically.

In an embodiment of the invention, a total thickness of each of thefirst type epitaxial structures and the corresponding first connectionportion is smaller than or equal to a total thickness of each of thesecond type epitaxial structures and the corresponding second connectionportion.

In an embodiment of the invention, a ratio of the thickness of each ofthe first connection portions to the thickness of the correspondingfirst type epitaxial structure is larger than 0.01 and smaller than orequal to 0.5.

In an embodiment of the invention, a ratio of the thickness of each ofthe first connection layers to a side length of the corresponding firsttype epitaxial structure is larger than 0.001 and smaller than or equalto 0.3.

In an embodiment of the invention, in the step (b), the first connectionlayer located between any two adjacent first type epitaxial structuresis removed via an etching process so as to form the first connectionportions separated from each other.

In an embodiment of the invention, in the step (a), the method offorming the first type epitaxial structures on the first substrateincludes (a-1) forming the first type epitaxial structures separatedfrom each other on a first growth carrier; (a-2) removing the firstgrowth carrier; (a-3) forming the first connection layer and the firstadhesive layer so as to bond the first type epitaxial structures and thefirst substrate together via the first adhesive layer.

In an embodiment of the invention, a step is further included betweenthe step (a-1) and the step (a-2):(a-1-1) forming a temporary fixinglayer so as to bond the first type epitaxial structures to a temporarysubstrate, wherein a bonding force between the temporary fixing layerand the temporary substrate is smaller than a bonding force between thefirst adhesive layer and the first substrate.

In an embodiment of the invention, the temporary fixing layer furthercovers the first type epitaxial structures.

In an embodiment of the invention, in the step (a), the method offorming the first type epitaxial structures on the first substrateincludes (a-1) forming the first type epitaxial structures separatedfrom each other on the first growth carrier; (a-2) forming the firstconnection layer and the first adhesive layer such that the first typeepitaxial structures and the first substrate are bonded together via thefirst adhesive layer; (a-3) removing the first growth carrier.

A micro light emitting diode device of the invention includes a circuitsubstrate, a plurality of first type epitaxial structures and aplurality of first connection portions. The epitaxial structures areseparately disposed on the circuit substrate and electrically connectedto the circuit substrate. The first connection portions are respectivelyand correspondingly disposed on a side of the first type epitaxialstructures away from the circuit substrate, wherein a ratio of thethickness of each of the first connection portions to the thickness ofthe corresponding first type epitaxial structure is larger than or equalto 0.01 and smaller than or equal to 0.5.

In an embodiment of the invention, the micro light emitting diode devicefurther includes a plurality of second type epitaxial structures and aplurality of second connection portions. The second type epitaxialstructures are separately disposed on the circuit substrate andelectrically connected to the circuit substrate. The second connectionportions are respectively and correspondingly disposed on a side of thesecond type epitaxial structures away from the circuit substrate,wherein a ratio of the thickness of the each of the second connectionportions to the thickness of the corresponding second type epitaxialstructures is larger than or equal to 0.01 and smaller than or equal to0.5, and the first type epitaxial structures and the second typeepitaxial structures respectively have different colors of light.

In an embodiment of the invention, a total thickness of each of thefirst type epitaxial structures and the corresponding first connectionportion is smaller than a total thickness of each of the second typeepitaxial structures and corresponding second connection portion.

In an embodiment of the invention, the thickness of each of the firsttype epitaxial structures is equal to the thickness of each of thesecond type epitaxial structures.

In an embodiment of the invention, the thickness of each of the firstconnection portion is equal to the thickness of each of the secondconnection portions.

In an embodiment of the invention, the total thickness of each of thefirst type epitaxial structures and the corresponding first connectionportion is equal to the total thickness of each of the second typeepitaxial structures and the corresponding second connection portion.

In an embodiment of the invention, the material of the first connectionportions is an insulating material.

In an embodiment of the invention, the material of the first connectionportions includes silicon nitride, or includes a group consisting ofoxides selected from silicon, aluminum, hafnium, zirconium, tantalum andtitanium.

In an embodiment of the invention, an orthogonal projection area of eachof the first connection portions on the circuit substrate is larger thanor equal to an orthogonal projection area of the corresponding firsttype epitaxial structure on the circuit substrate.

In an embodiment of the invention, the micro light emitting diode devicefurther includes a first insulating layer covering a side wall surfaceof each of the first type epitaxial structures.

In an embodiment of the invention, the first insulating layer and thefirst connection portion are formed of the same material, and thedensity of the first insulating layer is larger than the density of thefirst connection portion.

In an embodiment of the invention, the first insulating layer and thefirst connection layer are formed of different materials.

In an embodiment of the invention, a ratio of the thickness of the firstconnection portion to a side length of the corresponding first typeepitaxial structure is larger than or equal to 0.001 and smaller than orequal to 0.3.

In summary, in the manufacturing process of the micro light emittingdiode device of the invention, the relative positions of the pluralityof first type epitaxial structures may be fixed via the first connectionlayer; when the first adhesive layer is formed on the first connectionlayer and first substrate is adhered to the first adhesive layer in thesubsequent process, the relative positions of the first type epitaxialstructures are not shifted due to the effect of external force.Therefore, when the first type epitaxial structures are transferred tothe target substrate, each of the first type epitaxial structures can beprecisely aligned onto the target substrate. In other words, themanufacturing method of the micro light emitting diode device of theinvention facilitates to improve manufacturing efficiency and yield ofrate, and the obtained micro light emitting diode device has goodreliability.

In order to make the aforementioned features and advantages of thedisclosure more comprehensible, embodiments accompanying figures aredescribed in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 to FIG. 11 are cross-sectional views illustrating a manufacturingmethod of a micro light emitting diode device according to an embodimentof the invention.

FIG. 12 is a top view illustrating a micro light emitting diode deviceaccording to an embodiment of the invention.

FIG. 13 is a cross-sectional view illustrating a micro light emittingdiode device according to another embodiment of the invention.

FIG. 14 is a cross-sectional view illustrating a micro light emittingdiode device according to yet another embodiment of the invention.

FIG. 15 to FIG. 16 are cross-sectional views illustrating amanufacturing method of a micro light emitting diode device according tostill another embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

FIG. 1 to FIG. 11 are cross-sectional views illustrating a manufacturingmethod of a micro light emitting diode device according to an embodimentof the invention. First of all, referring to FIG. 1, a plurality offirst type epitaxial structures 120 a separated from each other areformed on a first growth carrier 100 a, wherein the first growth carrier100 a may be a sapphire substrate. In the embodiment, the first typeepitaxial structures 120 a partially cover one surface of the firstgrowth carrier 100 a.

The step of forming the first type epitaxial structures 120 a on thefirst growth carrier 100 a is exemplified as follows. First of all, anepitaxial structure layer is formed on the first growth carrier 100 a.Here, the step of forming the epitaxial structure layer is described asfollows. First of all, a semiconductor material layer is formed on thefirst growth substrate 100 a, and the semiconductor material layercovers one surface of the first growth carrier 100 a. The semiconductormaterial layer may be a multi-layered structure respectively doped witha group IIA element or a group IVA element so as to form a p-typesemiconductor layer or an n-type semiconductor layer respectively, ormay not be doped with anything; the invention provides no limitationthereto. Subsequently, an active material layer is formed on thesemiconductor material layer, and the active material layer covers onesurface of the semiconductor material layer. Thereafter, the othersemiconductor material layer is formed on the active material layer, andthe other semiconductor material layer covers one surface of the activematerial layer. The semiconductor material layer and the othersemiconductor material layer are respectively located on two oppositesides of the active material layer, and the other semiconductor materiallayer may be a multi-layered structure respectively doped with a groupIIA element or a group IVA element so as form the p-type semiconductorlayer or the n-type semiconductor layer, or may not be doped withanything; the invention provides no limitation thereto. In theembodiment, the material of the semiconductor material layer, the activematerial layer and the other semiconductor material layer may beselected from a group II-VI material such as zinc selenide (ZnSe), or agroup III-V material such as gallium nitride (GaN); the inventionprovides no limitation thereto.

Lastly, a resist-coating process, an exposing process, a lithographingprocess and an etching process are performed to pattern the epitaxialstructure layer (i.e., the semiconductor material layer, the activematerial layer and the other semiconductor material layer). In otherwords, the epitaxial structure layer in a specific region is removed soas to expose a portion of the surface of the first growth carrier 100 a,and the portion that is not removed defines the plurality of first typeepitaxial structures 120 a separated from each other. At this point, asshown in FIG. 1, each of the first type epitaxial structures 120 aincludes a first type semiconductor layer 122 a, a light emitting layer124 a and a second type semiconductor layer 126 a. The second typesemiconductor layer 126 a is connected to the first growth carrier 100a, and the light emitting layer 124 a is disposed on the second typesemiconductor layer 126 a. The first type semiconductor layer 122 a isdisposed on the light emitting layer 124 a, and the first typesemiconductor layer 122 a and the second type semiconductor layer 126 aare respectively located on two opposite sides of the light emittinglayer 124 a.

Furthermore, the semiconductor material layer doped with the group IIAelement or the group IVA element may form the second type semiconductorlayer 126 a, and the other semiconductor material layer doped with thegroup IIA element or the group IVA element may form the first typesemiconductor layer 122 a. If the semiconductor material layer isdisposed with the group IVA element such as silicon (Si) and forms then-type semiconductor layer 122 a, then the other semiconductor materiallayer may be doped with the group IIA element such as magnesium (Mg) andforms the p-type semiconductor layer. On other hand, if thesemiconductor material layer is doped with the group IIA element such asmagnesium (Mg) and forms the p-type semiconductor layer, then the othersemiconductor material layer may be doped with the group IVA elementsuch as silicon (Si) and forms the n-type semiconductor layer. That isto say, the first type semiconductor layer 122 a and the second typesemiconductor layer 126 a may be a combination of the p-typesemiconductor layer and the n-type semiconductor layer. On the otherhand, the light emitting layer 124 a may be a multiple quantum well(MQW) structure formed of the active material layer.

Next, referring to FIG. 2, a pad 130 a is formed on each of the firsttype epitaxial structures 120 a, wherein the pads 130 a and the firstgrowth carrier 100 a are respectively located on two opposite sides ofthe first type epitaxial structures 120 a, and each of the first typeepitaxial structures 120 a is electrically connected to a correspondingpad 130 a.

In the embodiment, the first type epitaxial structures 120 a may be ahorizontal light emitting diode, wherein each of the pads 130 a isdisposed on the corresponding first type semiconductor layer 122 a, andeach of the pads 130 a and the corresponding light emitting layer 124 aare respectively located on two opposite sides of the correspondingfirst type semiconductor layer 122 a. Each of the pads 130 a may includea first type electrode 132 a and a second type electrode 134 a and thetypes of electrical properties of the first type electrode 132 a and thesecond type electrode 134 a are different from each other, wherein thefirst type electrode 132 a is electrically connected to the first typesemiconductor layer 122 a, and the second type electrode 134 a iselectrically connected to the second type semiconductor layer 126 a. Thefirst type electrode 132 a and the second type electrode 134 a may be acombination of the p-type electrode and the n-type electrode. If thefirst type semiconductor layer 122 a is the p-type semiconductor layerand the second type semiconductor layer 126 a is the n-typesemiconductor layer, then the first type electrode 132 a is the p-typeelectrode and the second type electrode 134 a is the n-type electrode.On the other hand, if the first type semiconductor layer 122 a is then-type semiconductor layer, and the second type semiconductor layer 126a is the p-type semiconductor layer, then the first type electrode 132 ais the n-type electrode and the second type electrode 134 a is thep-type electrode.

In the embodiment, the first type epitaxial structures 120 a may bemicro light emitting diodes (Micro LED), wherein the maximum width ofeach of the first type epitaxial structures 120 a ranges from about 1 to100 μm, and preferably ranges from about 3 to 50 μm. On the other hand,the thickness of each of the first type epitaxial structures 120 aranges from about 1 to 6 μm, the thickness that is over-thick orover-slim affects the yield of rate in the subsequent process. In eachof the first type epitaxial structures 120 a, the thickness of thesecond type semiconductor layer 126 a may be larger than the thicknessof the first type semiconductor layer 122 a, wherein the thickness ofthe second type semiconductor layer 126 a ranges from about 1 to 5 μm,the thickness of the light emitting layer 124 a ranges from about 0.1 to1 μm, and the thickness of the first type semiconductor layer 122 aranges from about 0.1 to 0.5 μm, which should not be construed as alimitation to the invention. It should be specifically pointed out thata cross-section of the first type epitaxial structure 120 a describedhere is a rectangular shape. However, in another embodiment that is notshown, the cross-section of the first type epitaxial structure may be atrapezoid shape. The invention provides no limitation to the geometricalshape of the cross-section of the first type epitaxial structure.

Referring to FIG. 2, each of the first type epitaxial structures 120 ahas a side wall surface 125 a and a bonding surface 128 a connected toeach other, wherein the bonding surface 128 a is the surface where thepad 130 a is disposed, and the side wall surface 125 a and the bondingsurface 128 a may be perpendicular to each other, or an included anglebetween the side wall surface 125 a and the bonding surface 128 a may bean obtuse angle, thereby reducing the complexity of the subsequentmanufacturing process. In order to prevent moisture from affecting thefirst type epitaxial structures 120 a, it is optional to form a firstinsulating layer 140 a on the bonding surface 128 a and the side wallsurface 125 a of each of the first type epitaxial structures 120 a, buteach of the first insulating layers 140 a exposes the pad 130 a on thebonding surface 128 a of the corresponding first type epitaxialstructure 120 a for electrical bonding in the subsequent process. On theother hand, the first insulating layer 140 a located on the side wallsurface 125 a of the first type epitaxial structures 120 a is connectedto the surface of the first growth carrier 100 a located between any twoadjacent first type epitaxial structures 120 a. Here, the material ofthe first insulating layer 140 a may be silicon nitride or a groupconsisting of oxides selected from silicon, aluminum, hafnium,zirconium, tantalum and titanium, such as silicon dioxide (SiO₂) oraluminum oxide (Al₂O₃). In other embodiments, it is optional not to formthe first insulating layer on the bonding surface and the side wallsurface of the first type epitaxial structures such that the bondingsurface and the side wall surface of the first type epitaxial structuresare directly exposed to the outside.

Thereafter, referring to FIG. 3, a temporary fixing layer 150 a may beformed on the first growth carrier 100 a via a spin-coating process orother proper injecting process, and the temporary fixing layer 150 a isfurther disposed to cover the first type epitaxial structures 120 a, thepads 130 a and the first insulating layers 140 a. In the embodiment, thetemporary fixing layer 150 a is filled up into a gap between any twoadjacent first type epitaxial structures 120 a so as to cover thesurface of the first growth carrier 100 a in the gap. After thetemporary fixing layer 150 a is formed on the first growth carrier 100a, the temporary substrate 160 a is bonded (or adhered to) to thetemporary fixing layer 150 a, and the temporary substrate 160 a and thefirst growth carrier 100 a are respectively located on two oppositesides of the temporary fixing layer 150 a. It should be specificallyindicated that the temporary substrate 160 a and the first growthcarrier 100 a may be selected from the same material. For example, thetemporary substrate 160 a and the first growth carrier 100 a may be asapphire substrate so as to avoid deformation during boding process dueto difference in thermal expansion coefficient.

Next, referring to FIG. 4 and FIG. 5, the first growth carrier 100 a maybe removed via a laser lift-off process or other proper removingprocess, and the first connection layer 110 a is formed on the firsttype epitaxial structures 120 a and the temporary fixing layer 150 a,and the first connection layer 110 a and the temporary substrate 160 aare respectively located on two opposite sides of the temporary fixinglayer 150 a. With configuration of the first connection layer 110 a, therelative positions of the first type epitaxial structures 120 a can befixed. On the other hand, a ratio of the thickness of the firstconnection layer 110 a to the thickness of each of the first typeepitaxial structures 120 a is larger than 0.01 and smaller than or equalto 0.5. If the ratio is larger than 0.5, it becomes more difficult inthe subsequent process to form the plurality of first connectionportions separated from each other; if the ratio is smaller than orequal to 0.01, there may not be sufficient bonding force between thefirst connection layer 110 a and each of the first type epitaxialstructures 120 a. The first connection layer 110 a is directly connectedto the temporary fixing layer 150 a, the first insulating layer 140 aand the second type semiconductor layer 126 a. The material of the firstconnection layer 110 a may be an insulating material and the meltingpoint thereof is greater than 1000° C. to bear the high temperature andhigh pressure in the connecting process. For example, the material ofthe first connection layer 110 a may include silicon nitride (Si₃N₄), orincludes a group consisting of oxides selected from silicon, aluminum,hafnium, zirconium, tantalum and titanium, such as silicon dioxide(SiO₂) or aluminum oxide (Al₂O₃).

Subsequently, a first adhesive layer 170 a may be formed on the firstconnection layer 110 a via a spin-coating process or other properinjecting process, and a first substrate 180 a is connected to (oradhered to) the first adhesive layer 170 a. In other words, the firstsubstrate 180 a may be connected to the first connection layer 110 a viathe first adhesive layer 170 a, and the temporary substrate 160 a andthe first substrate 180 a are respectively located on two opposite sidesof the temporary fixing layer 150 a. Here, the bonding force between thetemporary fixing layer 150 a and the temporary substrate 160 a issmaller than the bonding force between the first adhesive layer 170 aand the first substrate 180 a. The melting point of the first connectionlayer 110 a is greater than the melting point of the temporary fixinglayer 150 a and the first adhesive layer 170 a. Since the temporaryfixing layer 150 a is covered and separated from each other, therelative positions of first type epitaxial structures 120 a can be fixedby the first connection layer 110 a. Therefore, when the first substrate180 a is connected to the first connection layer 110 a via the firstadhesive layer 170 a, even if the temporary fixing layer 150 a flows dueto being subjected to heat or force, the relative positions of the firsttype epitaxial structures 120 a are not shifted. Here, the Young'smodulus of the first connection layer 110 a is larger than the Young'smodulus of the first adhesive layer 170 a. Other than fixing therelative positions of the first type epitaxial structures 120 a to benot easily shifted via the first connection layer 110 a that is noteasily deformed, the first adhesive layer 170 a may also serve as abuffer when the first substrate 180 a is connected to the firstconnection layer 110 a. Here, the material of the first adhesive layer170 a is, for example, a polymer. It should be specifically indicatedthat the first substrate 180 a and the temporary substrate 160 a may beselected from the same material. For example, the first substrate 180 aand the temporary substrate 160 a may be a sapphire substrate so as toavoid deformation during the bonding process due to difference inthermal expansion coefficient.

Thereafter, referring to FIG. 6, the temporary substrate 160 a may beremoved via the laser lift-off process or other proper removing process,and the temporary fixing layer 150 a may be removed via a laser ablationprocess, an ultraviolet exposing process, a solution decompositionprocess or a heat decomposition process, thereby exposing the pads 130a, the first type epitaxial structures 120 a, the first insulatinglayers 140 a and the first connection layer 110 a located between anytwo adjacent first type epitaxial structures 120 a. Since the bondingforce between the temporary fixing layer 150 a and the temporarysubstrate 160 a is smaller than the bonding force between the firstadhesive layer 170 a and the first substrate 180 a, in the removingprocess, no effect is likely to be caused to the connection between thefirst adhesive layer 170 a and the first substrate 180 a.

Subsequently, referring to FIG. 6 and FIG. 7, the first connection layer110 a located between any two adjacent first type epitaxial structures120 a may be removed via a wet-etching process or other proper removingprocess so as to form a plurality of first connection portions 210 aseparated from each other, and the first connection portions 210 a arelight-transmittable. In terms of the relative configuration relationshipbetween each of the first type epitaxial structures 120 a and thecorresponding first connection portion 210 a, the first connectionportion 210 a is connected to the second type semiconductor layer 126 a,wherein the first connection portion 210 a and the light emitting layer124 a are respectively located on two opposite sides of the second typesemiconductor layer 126 a, and the second type semiconductor layer 126 aand the first type semiconductor layer 122 a are respectively located ontwo opposite sides of the light emitting layer 124 a.

Here, under the same etching condition, the etching rate of the materialof the first connection layer 110 a may be greater than the etching rateof the first insulating layer 140 a so as not to affect the firstinsulating layer 140 a disposed on each of the first type epitaxialstructures 120 a during the process of removing the first connectionlayer 110 a via etching. In an embodiment of the invention, the firstconnection layer 110 a and the first insulating layer 140 a may beformed of the same material, and the density of the material of thefirst connection layer 110 a is greater than the density of the materialof the first insulating layer 140 a. In another embodiment of theinvention, the first connection layer 110 a and the first insulatinglayer 140 a may be formed of different materials. For example, thematerial of the first connection layer 110 a may be silicon dioxide, andthe material of the first insulating layer 140 a may be silicon nitride;the invention provides no limitation thereto.

In the embodiment, a side surface 141 a of each of the first insulatinglayers 140 a is aligned with a side surface 211 a of the firstconnection portion 210 a of the corresponding first type epitaxialstructures 120 a. Therefore, the orthogonal projection area of each ofthe first connection portions 210 a on the first substrate 180 a isequal to the orthogonal projection area of the corresponding first typeepitaxial structure 120 a on the first substrate 180 a. In other words,the orthogonal projection of each of the first type epitaxial structures120 a on the first substrate 180 a completely overlaps the orthogonalprojection of the corresponding first connection portion 210 a on thefirst substrate 180 a. In other embodiments, the side surface of each ofthe first connection portions may slightly surpass the side surface ofthe first insulating layer of the corresponding first type epitaxialstructure; therefore, the orthogonal projection area of each of thefirst connection portions on the first substrate is larger than theorthogonal projection area of the corresponding first type epitaxialstructure on the first substrate. Preferably, a ratio of the orthogonalprojection area of each of the first connection portions on the firstsubstrate to the orthogonal projection area of the corresponding firsttype epitaxial structure on the first substrate is smaller than or equalto 1.1. If the ratio is larger than 1.1, then the first type epitaxialstructures cannot be closely arranged, which affects the applicationefficiency of the first type epitaxial structures in the micro lightemitting diode device in the subsequent process. That is to say, theorthogonal projection of each of the first type epitaxial structures onthe first substrate falls within the orthogonal projection of thecorresponding first connection portion on the first substrate.

Referring to FIG. 8, at least a portion of the first type epitaxialstructures 120 a are configured to electrically bond the correspondingpad 130 a to the target substrate 200 via a bonding process such as athermal bonding process. Here, only a portion of the first typeepitaxial structures 120 a are bonded to the target substrate 200 viathe bonding process. In an embodiment that is not shown, the whole firsttype epitaxial structure may be transferred to the target substrate.Referring to FIG. 9, the first substrate 180 a is removed via a laserlift-off process or other proper removing process. Next, the firstadhesive layer 170 a is removed via the wet-etching process or otherproper removing process. In the embodiment, each of the first connectionportions 210 a is disposed on the second type second semiconductor layer126 a, wherein the ratio of the thickness of each of the firstconnection portions 210 a to the thickness of the corresponding firsttype epitaxial structure 120 a is larger than 0.01 and smaller than orequal to 0.5.

In the manufacturing process, the relative positions of the first typeepitaxial structures 120 a are not shifted. Therefore, when the firsttype epitaxial structures 120 a are transferred onto the targetsubstrate 200, the pads 130 a on the first type epitaxial structures 120a can be precisely aligned with an electrode bonding layer (not shown)on the target substrate 200, thereby improving manufacturing efficiencyand yield of rate.

Referring to FIG. 10, in the embodiment, after the first type epitaxialstructures 120 a are transferred onto the target substrate 200, a stepof forming a plurality of second type epitaxial structures 120 a on asecond substrate 180 b is further involved. The second type epitaxialstructures 120 b are separated from each other, wherein a secondconnection portion 210 b is configured between each of the second typeepitaxial structures 120 b and the second substrate 180 b, and thesecond connection portions 210 b are connected to the second substrate180 a via a second adhesive layer 170 b. The first type epitaxialstructures 120 a and the second type epitaxial structures 120 b may havedifferent light colors. Thereafter, at least a portion of the secondtype epitaxial structures 120 b are configured to electrically bondcorresponding pads 130 b to the target substrate 200 via a bondingprocess such as a thermal bonding process. It should be specificallypointed out that the steps illustrated in FIG. 1 to FIG. 7 may serve asreference for the steps of forming the second type epitaxial structures120 b and connecting the second connection portions 210 b to the secondsubstrate 180 b via the second adhesive layer 170 b; no repetition isincorporated herein. After at least the portion of the second typeepitaxial structures 120 b are configured to electrically bond thecorresponding pads 130 b to the target substrate 200 via the bondingprocess, the second substrate 180 b may be removed via a laser lift-offprocess or other proper removing process. Next, the second adhesivelayer 170 b is removed by a wet-etching process or other proper removingprocess. It should be specifically pointed out that each of the secondconnection portions 210 b and the corresponding second type epitaxialstructure 120 b also have the same or similar structural features aseach of the first connection portions 210 a and the corresponding thefirst type epitaxial structure 120 a.

Here, the total thickness of each of the first type epitaxial structures120 a and the corresponding first connection portion 210 a is smallerthan the total thickness of each of the second type epitaxial structures120 b and the corresponding second connection portion 210 b. On thepremise that the thickness of each of the first type epitaxialstructures 120 a is equivalent to the thickness of each of the secondtype epitaxial structures 120 b, the thickness of each of the firstconnection portions 210 a is smaller than the thickness of each of thesecond connection portions 210 b, and each of the first type epitaxialstructures 120 a is electrically bonded to the target substrate 200 inorder and each of the second type epitaxial structures 120 b iselectrically bonded to the target substrate 200. That is to say, basedon the order of the total thickness of the epitaxial structure and thecorresponding connection portion, each of the first type epitaxialstructures 120 a and the corresponding first connection portion 210 awith the least total thickness are transferred onto the target substrate200 first, then each of the second type epitaxial structures 120 b andthe corresponding second connection portion 210 b with a more totalthickness are transferred onto the target substrate 200. Since the totalthickness of each of the first type epitaxial structures 120 a and thecorresponding first connection portion 210 a that are first transferredonto the target substrate 200 is thinner, when each of the second typeepitaxial structures 120 and the corresponding second connection portion210 are transferred onto the target substrate 200 subsequently, thesecond adhesive layer 170 b is not brought into contact with the firsttype epitaxial structures 120 a and the first connection portion 210 athat are already transferred onto the target substrate 200 so as toavoid causing damage to the first type epitaxial structures 120 a andthe first connection portions 210 a that are already transferred ontothe target substrate 200 due to pressure.

Further referring to FIG. 11, FIG. 11 schematically illustrates anaspect that a third type epitaxial structure 120 c and a correspondingthird connection portion 210 c with the greatest total thickness aretransferred onto the target substrate 200. For example, the stepsdescribed in FIG. 1 to FIG. 10 may serve as reference for the steps offorming the third type epitaxial structure 120 c and the correspondingthird connection portion 210 c as well as transferring each of thesecond type epitaxial structures 120 b and the corresponding secondconnection portion 210 b onto the target substrate 200; no repetition isincorporated herein. It should be specifically indicated that each ofthe third connection portions 210 c and the corresponding third typeepitaxial structure 120 c also have the same or similar structuralfeatures as each of the first connection portions 210 a and thecorresponding first type epitaxial structure 120 a. Here, before each ofthe third type epitaxial structures 120 c and the corresponding thirdconnection portion 210 c are transferred onto the target substrate 200,each of the first type epitaxial structures 120 a and the correspondingfirst connection portion 210 a as well as each of the second typeepitaxial structures 120 b and the corresponding second connectionportion 210 b are transferred onto the target substrate 200 in order.

Since the total thickness of each of the third type epitaxial structures120 c and the corresponding third connection portion 210 c is thethickest, when each of the third type epitaxial structures 120 c and thecorresponding third connection portion 210 c are transferred onto thetarget substrate 200, a third adhesive layer (not shown) is not broughtinto contact with the first type epitaxial structures 120 a and thefirst connection portions 210 a and the second type epitaxial structures120 b and the second connection portions 210 b that are alreadytransferred onto the target substrate 20, thereby avoiding causingdamage to the first type epitaxial structures 120 a and the firstconnection portions 210 a as well as the second type epitaxialstructures 120 b and the second connection portions 210 b that arealready transferred onto the target substrate 200 due to pressure.

In the embodiment, the connection portions (including the firstconnection portions 210 a, the second connection portions 210 b and thethird connection portions 210 c) and the target substrate 200 arerespectively located on two opposite sides of the epitaxial structures(including the first type epitaxial structures 120 a, the second typeepitaxial structures 120 b and the third type epitaxial structures 120c). For example, the target substrate 200 may be a circuit substrate.The circuit substrate is practically implemented as a display panel suchas a contemporary metal oxide semiconductor (CMOS) substrate, a liquidcrystal on silicon (LCOS) substrate, a thin film transistor (TFT)substrate or other substrate having a working circuit, wherein a sidewhere the circuit substrate (i.e., the target substrate 200) is bondedto the epitaxial structures (including the first type epitaxialstructures 120 a, the second type epitaxial structures 120 b and thethird type epitaxial structures 120 c) is provided with an electrodebonding layer (not shown), and each of the epitaxial structures(including the first type epitaxial structures 120 a, the second typeepitaxial structures 120 b and the third type epitaxial structures 120c) is electrically bonded to the electrode bonding layer (not shown) viathe corresponding pad (including pads 130 a to 130 c) using a flip-chipbonding process so as to be electrically connected to the targetsubstrate 200. Specifically, the first type epitaxial structures 120 a,the second type epitaxial structures 120 b and the third type epitaxialstructures 120 c may have different light colors. For example, the firsttype epitaxial structures 120 a, the second type epitaxial structures120 b and the third type epitaxial structures 120 c may be a combinationof a red light micro epitaxial structure (or referred to as red lightmicro light emitting diode), a green light micro epitaxial structure (orreferred to as green light micro light emitting diode) and a blue lightmicro epitaxial structure (or referred to as blue light micro lightemitting diode).

In the manufacturing process, the relative positions of the epitaxialstructures (including the first type epitaxial structures 120 a, thesecond type epitaxial structures 120 b and the third type epitaxialstructures 120 c) are not shifted. Therefore, when the epitaxialstructures (including the first type epitaxial structures 120 a, thesecond type epitaxial structures 120 b and the third type epitaxialstructures 120 c) are transferred onto the target substrate 200, the pad(including the boning pads 130 a to 130 c) on each of the epitaxialstructures (including the first type epitaxial structures 120 a, thesecond type epitaxial structures 120 b and the third type epitaxialstructures 120 c) can be precisely aligned with the electrode bondinglayer (not shown) on the target substrate 200, thereby improvingmanufacturing efficiency and yield of rate.

In the embodiment, the orthogonal projection area of each of the firstconnection portions 210 a on the target substrate 200 is equivalent tothe orthogonal projection area of the corresponding first type epitaxialstructure 120 a on the target substrate 200. In other words, theorthogonal projection of each of the first type epitaxial structures 120a on the target substrate 200 completely overlaps the orthogonalprojection of the corresponding first connection portion 210 a on thetarget substrate 200. It should be specifically indicated that each ofthe second connection portions 210 b and the corresponding second typeepitaxial structure 120 b also have the same or similar structuralfeatures as described above, and each of the third connection portions2110 c and the corresponding third type epitaxial structure 120 c alsohave the same or similar structural features as described above. Inother embodiment, the side surface of each of the connection portionsmay slightly surpass the side surface of the insulating layer on thecorresponding epitaxial structure; therefore, the orthogonal projectionarea of each of the connection portions on the target substrate islarger than the orthogonal projection area of the correspondingepitaxial structure on the circuit substrate. Preferably, the proportionof the orthogonal projection area of each of the connection portions onthe target substrate to the orthogonal projection area of thecorresponding epitaxial structure on the target substrate is larger than1 and smaller than or equal to 1.1. That is to say, the orthogonalprojection of each of the epitaxial structure on the target substratefalls within the orthogonal projection of the corresponding connectionportion on the target substrate.

The above manufacturing step shows that the connection portions(including the first connection portions 210 a, the second connectionportions 210 b and the third connection portions 210 c) separated fromeach other are formed by partially removing the connection layers(including the first connection layers 110 a, the second connectionlayers (not shown) and the third connection layers (not shown)), whereina ratio of the thickness of each of the connection portions (includingthe first connection portions 210 a, the second connection portions 210b and the third connection portions 210 c) to the thickness of thecorresponding epitaxial structures (including the first type epitaxialstructures 120 a, the second type epitaxial structures 120 b and thethird type epitaxial structures 120 c) is larger than 0.01 and smallerthan or equal to 0.5, which represents that the ratio of the thicknessof the connection layers (including the first connection layers 110 a,the second connection layers (not shown) and the third connection layers(not shown)) to the thickness of the corresponding epitaxial structures(including the first type epitaxial structures 120 a, the second typeepitaxial structures 120 b and the third type epitaxial structures 120c) is also larger than 0.01 and smaller than or equal to 0.5. If theratio of the thickness of the connection layers (including the firstconnection layers 110 a, the second connection layers (not shown) andthe third connection layers (not shown)) to the thickness of thecorresponding epitaxial structures (including the first type epitaxialstructures 120 a, the second type epitaxial structures 120 b and thethird type epitaxial structures 120 c) is larger than 0.5, then it isdifficult to carry out the process of partially removing the connectionlayers (including the first connection layers 110 a, the secondconnection layers (not shown) and the third connection layers (notshown)). If the thickness ratio is smaller than or equal to 0.01, thebonding force between the connection layers (including the firstconnection layers 110 a, the second connection layers (not shown) andthe third connection layers (not shown)) and the corresponding epitaxialstructures (including the first type epitaxial structures 120 a, thesecond type epitaxial structures 120 b and the third type epitaxialstructures 120 c) becomes too weak. Specifically, the thickness of eachof the epitaxial structures (including the first type epitaxialstructures 120 a, the second type epitaxial structures 120 b and thethird type epitaxial structures 120 c) is 5 μm for example, and thethickness of the corresponding connection portions (including the firstconnection layers 110 a, the second connection layers (not shown) andthe third connection layers (not shown)) is 0.1 to 2 μm for example,which should not be construed as a limitation to the invention. Itshould be specifically pointed out that the ratio of the thickness ofthe connection portions (including the first connection portions 210 a,the second connection portions 210 b and the third connection portions210 c) to the maximum width of the corresponding epitaxial structures(including the first type epitaxial structures 120 a, the second typeepitaxial structures 120 b and the third type epitaxial structures 120c) ranges from 0.001 to 0.3. When the ratio is smaller than 0.001, thethickness of the connection portions (including the first connectionportions 210 a, the second connection portions 210 b and the thirdconnection portions 210 c) is too thin, and the insufficient bondingforce may cause the relative positions of the epitaxial structures(including the first type epitaxial structures 120 a, the second typeepitaxial structures 120 b and the third type epitaxial structures 120c) to change during process. When the ratio is larger than 0.3, thethickness of the connection portions (including the first connectionportions 210 a, the second connection portions 210 b and the thirdconnection portions 210 c) is too thick, which is likely to make itdifficult to carry out the process of partially removing the over-thickconnection layers (including the first connection layers 110 a, thesecond connection layers (not shown) and the third connection layers(not shown)), and reduces the yield rate of the process of forming eachof the connection portions (including the first connection portions 210a, the second connection portions 210 b and the third connectionportions 210 c). Preferably, when the maximum width of the epitaxialstructures (including the first type epitaxial structures 120 a, thesecond type epitaxial structures 120 b and the third type epitaxialstructures 120 c) is smaller than 50 μm, a ratio of the thickness of theconnection portions (including the first connection portions 210 a, thesecond connection portions 210 b and the third connection portions 210c) to the maximum width of the corresponding epitaxial structures(including the first type epitaxial structures 120 a, the second typeepitaxial structures 120 b and the third type epitaxial structures 120c) ranges from 0.002 to 0.2. When the maximum width of the epitaxialstructures (including the first type epitaxial structures 120 a, thesecond type epitaxial structures 120 b and the third type epitaxialstructures 120 c) is larger than or equal to 50 μm, a ratio of thethickness of the connection portions (including the first connectionportions 210 a, the second connection portions 210 b and the thirdconnection portions 210 c) to the maximum width of the correspondingepitaxial structures (including the first type epitaxial structures 120a, the second type epitaxial structures 120 b and the third typeepitaxial structures 120 c) ranges from 0.001 to 0.04.

In the embodiment, the micro light emitting diode device 10 includes thecircuit substrate (i.e., target substrate 200), a plurality of epitaxialstructures (including the first type epitaxial structures 120 a, thesecond type epitaxial structures 120 b and the third type epitaxialstructures 120 c), a plurality of pads (including pads 130 a to 130 c)and a plurality of connection portions (including the first connectionportions 210 a, the second connection portions 210 b and the thirdconnection portions 210 c). The epitaxial structures (including thefirst type epitaxial structures 120 a, the second type epitaxialstructures 120 b and the third type epitaxial structures 120 c) aredisposed on the circuit substrate (i.e., target substrate 200) andseparated from each other. The pads (including pads 130 a to 130 c) arerespectively disposed on the epitaxial structures (including the firsttype epitaxial structures 120 a, the second type epitaxial structures120 b and the third type epitaxial structures 120 c), and the epitaxialstructures (including the first type epitaxial structures 120 a, thesecond type epitaxial structures 120 b and the third type epitaxialstructures 120 c) are electrically bonded to the circuit substrate(i.e., target substrate 200) via the corresponding pads (including pads130 a to 130 c). The connection portions (including the first connectionportions 210 a, the second connection portions 210 b and the thirdconnection portions 210 c) are respectively disposed on the epitaxialstructures (including the first type epitaxial structures 120 a, thesecond type epitaxial structures 120 b and the third type epitaxialstructures 120 c), and provided with light-guiding function so that theepitaxial structures have a better light emitting efficiency. Morespecifically, the refractive index of the connection portions (includingthe first connection portions 210 a, the second connection portions 210b and the third connection portions 210 c) may be smaller than therefractive index of the epitaxial structures (including the first typeepitaxial structures 120 a, the second type epitaxial structures 120 band the third type epitaxial structures 120 c) and larger than therefractive index of air, so as avoid total reflection generated in theepitaxial structure during light emission and affect the light emittingefficiency. The connection portions (including the first connectionportions 210 a, the second connection portions 210 b and the thirdconnection portions 210 c) and the circuit substrate (i.e., targetsubstrate 200) are respectively located on two opposite sides of theepitaxial structures (including the first type epitaxial structures 120a, the second type epitaxial structures 120 b and the third typeepitaxial structures 120 c), and the epitaxial structures (including thefirst type epitaxial structures 120 a, the second type epitaxialstructures 120 b and the third type epitaxial structures 120 c) and thecircuit board (i.e., target substrate 200) are respectively located ontwo opposite sides of the pads (including pads 130 a to 130 c). Thematerial of the connection portions (including the first connectionportions 210 a, the second connection portions 210 b and the thirdconnection portions 210 c) may be an insulating material and the meltingpoint thereof is greater than 1000° C. For example, the material of theconnection portions (including the first connection portions 210 a, thesecond connection portions 210 b and the third connection portions 210c) may include silicon nitride, or includes a group consisting of oxidesselected from silicon, aluminum, hafnium, zirconium, tantalum andtitanium, such as silicon dioxide or aluminum oxide.

FIG. 12 is a top view illustrating a micro light emitting diode deviceaccording to an embodiment of the invention. Referring to FIG. 12, inthe embodiment, the micro light emitting diode device 10 is practicallyimplemented as a micro light emitting diode display panel. Practically,with the manufacturing steps described above, the first type epitaxialstructure 120 a, the second type epitaxial structure 120 b and the thirdtype epitaxial structure 120 c can be obtained respectively. Meanwhile,the first type epitaxial structure 120 a, the second type epitaxialstructure 120 b and the third type epitaxial structure 120 c mayrespectively have different light colors. For example, the first typeepitaxial structure 120 a, the second type epitaxial structure 120 b andthe third type epitaxial structure 120 c may be a combination of a redlight micro epitaxial structure (or referred to as red light micro lightemitting diode), a green light micro epitaxial structure (or referred toas green light micro light emitting diode) and a blue light microepitaxial structure (or referred to as blue light micro light emittingdiode). The micro light emitting diode device 10 can obtained bytransferring the first type epitaxial structure 120 a, the second typeepitaxial structure 120 b and the third type epitaxial structure 120 crespectively to the circuit substrate (i.e., target substrate 200).Specifically, the first type epitaxial structure 120 a are formed as onecolumn on the circuit substrate (i.e., target substrate 200); the secondtype epitaxial structure 120 b are formed as one column on the circuitsubstrate (i.e., target substrate 200); and the third type epitaxialstructure 120 c are formed as one column on the circuit substrate (i.e.,target substrate 200). Therefore, in a row direction RD perpendicular tothe column direction CD, the arrangement in the order of the first typeepitaxial structure 120 a, the second type epitaxial structure 120 b andthe third type epitaxial structure 120 c may be repeated. In otherembodiment, the sequence of arrangement of the red light micro lightemitting diode, the green light micro light emitting diode and the bluelight micro light emitting diode in the row direction may be adjusteddepending on the actual requirement; the invention provides nolimitation thereto.

The circuit substrate (i.e., target substrate 200) may be divided into adisplay area 201 and a non-display area 202. The first type epitaxialstructure 120 a, the second type epitaxial structure 120 b and the thirdtype epitaxial structure 120 c arranged adjacently in sequence in therow direction RD may construct a pixel structure P, and disposed in thedisplay area 201. In other words, at least three epitaxial structuresmay construct a pixel structure P. On the other hand, a data drivingcircuit DL and a scan driving circuit SL are disposed in the non-displayarea 202, wherein the data driving circuit DL is electrically connectedto each of the pixel structures P to transmit a data signal to the firsttype epitaxial structure 120 a, the second type epitaxial structure 120b and the third type epitaxial structure 120 c in each of the pixelstructures, wherein the scan driving circuit SL is electricallyconnected to each of the pixel structures P to transmit a scan signal tothe first type epitaxial structure 120 a, the second type epitaxialstructure 120 b and the third type epitaxial structure 120 c in each oneof the pixel structures. Each of the pixel structures P is electricallyconnected a control device CTR via the data driving circuit DL and thescan driving circuit SL, wherein the control device CTR is configured tosend a control signal to the data driving circuit DL and the scandriving circuit SL. The data driving circuit DL and the scan drivingcircuit SL that receive the control signal respectively send the datasignal and the scan signal to each of the pixel structures P so as tocontrol and drive the light emitted by the first type epitaxialstructure 120 a, the second type epitaxial structure 120 b and the thirdtype epitaxial structure 120 c in each of the pixel structures P.

FIG. 13 is a cross-sectional view illustrating a light emitting diodedevice according to another embodiment of the invention. Referring toFIG. 13, a light emitting device 10A in the embodiment is substantiallysimilar to the light emitting device 10 in the previous embodiment. Thedifference between the two is that the thickness of each of firstconnection portions 210 a, the thickness of each of second connectionportions 210 b and the thickness of each of third connection portions210 c are equivalent to one another. On the premise that the totalthickness of each of first type epitaxial structures 120 a and thecorresponding first connection portions 210 a is smaller than the totalthickness of each of second type epitaxial structures 120 b and thecorresponding second connection portions 210 b, and the total thicknessof each of second type epitaxial structures 120 b and the correspondingsecond connection portion 210 b is smaller than the total thickness ofeach of third type epitaxial structures 120 c and the correspondingthird connection portion 210 c, the thickness of each of first typeepitaxial structures 120 a is smaller than the thickness of each ofsecond type epitaxial structures 120 b, and the thickness of each ofsecond type epitaxial structures 120 b is smaller than the thickness ofeach of third type epitaxial structures 120 c. On the other hand, theembodiments provided above may serve as reference for the sequence inwhich the epitaxial structures are transferred onto the target substrate200; no repetition is incorporated wherein. With the design that thethickness of each of first connection portions 210 a, the thickness ofeach of second connection portions 210 b and the thickness of each ofthird connection portions 210 c are equivalent to one another, themanufacturing process may be simpler.

FIG. 14 is a cross-sectional view illustrating a micro light emittingdiode device according to yet another embodiment of the invention.Referring to FIG. 14, a light emitting device 10B in the embodiment issubstantially similar to the light emitting device 10 in the previousembodiment. The difference between the two is that the total thicknessof each of first type epitaxial structures 120 a and corresponding firstconnection portion 210 a, the total thickness of each of second typeepitaxial structures 120 b and corresponding second connection portion210 b and the total thickness of each of third type epitaxial structures120 c and corresponding third connection portion 210 c are equivalent toone another. The thickness of each of first type epitaxial structures120 a is smaller than the thickness of each of second type epitaxialstructures 120 b, and the thickness of each of second type epitaxialstructures 120 b is smaller than the thickness of each of third typeepitaxial structures 120 c. Therefore, the thickness of each of firstconnection portions 210 a is larger than the thickness of each of secondconnection portions 210 b, and the thickness of each of secondconnection portions 210 b is larger than the thickness of each of thethird connection portions 210 c. According to the thickness of the firstconnection portions 210 a, the second connection portions 210 b and thethird connection portions 210 c, each of the first type epitaxialstructures 120 a provided with the first connection portion 210 a havingthe greatest thickness is transferred onto the circuit substrate (i.e.,target substrate 200) first; then each of the second type epitaxialstructures 120 b provided with the second connection portion 210 bhaving less thickness is transferred onto the circuit substrate (i.e.,target substrate 200); lastly each of third type epitaxial structures120 c provided with the third connection portion 210 c having the leastthickness is transferred onto the circuit substrate (i.e., targetsubstrate 200). Since the epitaxial structure that is transferred ontothe circuit substrate (i.e., target substrate 200) first is providedwith the connection portion having a thicker thickness, a bufferingeffect can be rendered so as to avoid causing damage to the epitaxialstructure that is already transferred to the circuit substrate (i.e.,target substrate 200) due to pressure. It should be specificallyindicated that the Young's modulus of the first connection portion 210a, the second connection portion 210 b and the third connection portion210 c are respectively smaller than the Young's modulus of the firsttype epitaxial structure 120 a, the second type epitaxial structure 120b and the third type epitaxial structure 120 c, such that a betterbuffering effect can be rendered.

FIG. 15 to FIG. 16 are cross-sectional views illustrating amanufacturing method of a micro light emitting diode device according tostill another embodiment of the invention. Referring to FIG. 15 to FIG.16, the manufacturing method of the light emitting device of theembodiment is substantially similar to the manufacturing method of thelight emitting device 10 of the previous embodiment. The differencebetween the two is that, in the light emitting device of the embodiment,after the first type epitaxial structure 120 a separated from each otheris formed on the first growth carrier 100 a, a first connection layer1101 is formed. Thereafter, a temporary fixing layer 150 a is formed,and the first type epitaxial structures 120 a are bonded to a temporarysubstrate 160 a via the temporary fixing layer 150 a.

Thereafter, referring to FIG. 16, the first growth carrier 100 a isremoved. That is to say, the first connection layer 1101 of theembodiment is formed before the first growth carrier 100 a is removed.The steps illustrated in FIG. 5 to FIG. 9 may serve as reference for thesubsequent step where the first type epitaxial structure 120 a iselectrically bonded to the target substrate 200; no repetition isincorporated herein. With the first connection layer 1101, the relativepositions of the first type epitaxial structures 120 a can be fixed,such that the first type epitaxial structures 120 a can be preciselyaligned on the target substrate 200. It should be specifically pointedout that the first connection layer 1101 that is formed on each of firsttype epitaxial structures 120 a may expose the pad 130 a on thecorresponding first type epitaxial structure 120 a so as to beelectrically bonded to the target substrate in the subsequent process.

In summary, in the manufacturing process of the micro light emittingdiode device of the invention, the relative positions of the pluralityof first type epitaxial structures may be fixed via the first connectionlayer, when the first adhesive layer is formed on the first connectionlayer and the first substrate is adhered to the first adhesive layer inthe subsequent process, even if the first adhesive layer flows due tobeing subjected to heat or force, the relative positions of the firsttype epitaxial structures are not shifted due to the impact caused bythe first adhesive layer that flows. Therefore, when the first typeepitaxial structures are transferred onto the target substrate, the padon each of first type epitaxial structures can be precisely aligned withthe electrode bonding layer on the target substrate. In other words, themanufacturing method of the micro light emitting diode device of theinvention facilitates to improve manufacturing efficiency and yield ofrate; moreover, the obtained micro light emitting diode device can havegood reliability.

Furthermore, in terms of configuration of thickness, the total thicknessof one of at least two epitaxial structures that can emit differentlight colors and the corresponding connection portion may be set to besmaller than the total thickness of the other of the two epitaxialstructures and the corresponding connection portion. Also, in thetransferring process, one of the epitaxial structures and thecorresponding connection portion with the thinner total thickness aretransferred to the circuit substrate first, then the other one of theepitaxial structures and the corresponding connection portion with athicker thickness are transferred to the circuit substrate, so as toavoid causing damage to the epitaxial structure and the connectionportion thereon that are already transferred onto the circuit substratedue to pressure.

Alternatively, the total thickness of at least one of the two epitaxialstructures that can emit different light colors and the correspondingconnection portion may be set to be equivalent to the total thickness ofthe two epitaxial structures and the corresponding connection portion.Also, in the transferring process, one of the epitaxial structureshaving the connection portion with a thicker thickness is transferred tothe target substrate first, then the other one of the epitaxialstructures having the connection portion with a thinner thickness istransferred to the target substrate. Since the epitaxial structure thatis already transferred onto the circuit substrate is provided with theconnection portion having a thicker thickness, a buffering effect can berendered so as to avoid causing damage to the epitaxial structure thatis already transferred onto the target substrate due to pressure.

Although the invention has been disclosed by the above embodiments, theembodiments are not intended to limit the invention. It will be apparentto those skilled in the art that various modifications and variationscan be made to the structure of the invention without departing from thescope or spirit of the invention. Therefore, the protecting range of theinvention falls in the appended claims.

What is claimed is:
 1. A manufacturing method of a micro light emittingdiode device, comprising: (a) forming a plurality of first typeepitaxial structures on a first substrate, and the plurality of firsttype epitaxial structures are separated from each other, wherein a firstconnection layer and a first adhesive layer are configured between theplurality of first type epitaxial structures and the first substrate,the first connection layer is connected to the plurality of first typeepitaxial structures, and the first adhesive layer is located betweenthe first connection layer and the first substrate, wherein a Young'smodulus of the first connection layer is larger than a Young's modulusof the first adhesive layer; and (b) removing the first connection layerlocated between any two adjacent of the plurality of first typeepitaxial structures so as for form a plurality of first connectionportions separated from each other, wherein each of the plurality offirst connection portions is respectively connected to each of thecorresponding first type epitaxial structures.
 2. The manufacturingmethod of the micro light emitting diode device according to claim 1,further comprising: (c) bonding a portion of the plurality of first typeepitaxial structures to a target substrate electrically.
 3. Themanufacturing method of the micro light emitting diode device accordingto claim 1, further comprising: (d) forming a plurality of second typeepitaxial structures on a second substrate, and the plurality of secondtype epitaxial structures are separated from each other, wherein asecond connection layer and a second adhesive layer are configuredbetween the plurality of second type epitaxial structures and the secondsubstrate, the second connection layer is connected to the plurality ofsecond type epitaxial structures, and the second adhesive layer islocated between the second connection layer and the second substrate,wherein a Young's modulus of the second connection layer is larger thana Young's modulus of the second adhesive layer; and (e) removing thesecond connection layer located between any two adjacent of theplurality of second type epitaxial structures so as to form a pluralityof second connection portions separated from each other, wherein each ofthe plurality of second connection portions is respectively connected toeach of the corresponding second type epitaxial structures.
 4. Themanufacturing method of the micro light emitting diode device accordingto claim 3, further comprising: (f) bonding a portion of the pluralityof first type epitaxial structures in the step (b) to a target substrateelectrically; and (g) bonding a portion of the plurality of second typeepitaxial structures in the step (e) to the target substrateelectrically.
 5. The manufacturing method of the micro light emittingdiode device according to claim 4, wherein a total thickness of each ofthe plurality of first type epitaxial structures and each of thecorresponding first connection portions is smaller than or equal to atotal thickness of each of the plurality of second type epitaxialstructures and each of the corresponding second connection portions. 6.The manufacturing method of the micro light emitting diode deviceaccording to claim 1, wherein a ratio of a thickness of each of theplurality of first connection portions to a thickness of each of thecorresponding first type epitaxial structures is larger than 0.01 andsmaller than or equal to 0.5.
 7. The manufacturing method of the microlight emitting diode device according to claim 1, wherein a ratio of athickness of each of the plurality of first connection portions to aside length of each of the corresponding first type epitaxial structuresis larger than 0.001 and smaller than or equal to 0.3.
 8. Themanufacturing method of the micro light emitting diode device accordingto claim 1, in the step (b), the first connection layer located betweenany two adjacent of the plurality of first type epitaxial structures isremoved via an etching process so as to form the plurality of firstconnection portions separated from each other.
 9. The manufacturingmethod of the micro light emitting diode device according to claim 1, inthe step (a), the method of forming the plurality of first typeepitaxial structures on the first substrate comprises: (a-1) forming theplurality of first type epitaxial structures separated from each otheron a first growth carrier; (a-2) removing the first growth carrier; and(a-3) forming the first connection layer and the first adhesive layer,bonding the plurality of first type epitaxial structures to the firstsubstrate via the first adhesive layer.
 10. The manufacturing method ofthe micro light emitting diode device according to claim 9, a step isfurther comprised between the step (a-1) and the step (a-2): (a-1-1)forming a temporary fixing layer so as to bond the plurality of firsttype epitaxial structures to a temporary substrate, wherein a bondingforce between the temporary fixing layer and the temporary substrate issmaller than a bonding force between the first adhesive layer and thefirst substrate.
 11. The manufacturing method of the micro lightemitting diode device according to claim 10, wherein the temporaryfixing layer further covers the plurality of first type epitaxialstructures.
 12. The manufacturing method of the micro light emittingdiode device according to claim 1, in the step (a), the method forforming the plurality of first type epitaxial structures on the firstsubstrate comprises: (a-1) forming the plurality of first type epitaxialstructures separated from each other on a first growth carrier; (a-2)forming the first connection layer and the first adhesive layer, bondingthe plurality of first type epitaxial structures to the first substratevia the first adhesive layer; and (a-3) removing the first growthcarrier.